Reactive Spring (JUG CH)

These slides explain reactive programming concepts, using Project Reactor and Spring to build asynchronous, non-blocking applications.

Transcript

1. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
   Reactive Spring
   Mark Paluch, Pivotal Software, Inc.
   @mp911de
   

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2. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
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   What is Reactive
   Programming?
   

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3. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
   Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
   ! Makes assumptions over resource usage
   ! Developers are in charge of resource usage efficiency
   3
   Imperative programming
   

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4. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
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   ! Container calls code on a Thread
   ! Thread is occupied
   ! Thread is released at the end of work
   4
   Imperative: Web applications
   

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5. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
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   Use Case: Synchronous fetch model
   5
   Service
   App
   Data store
   App
   Service
   

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6. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
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   ! Reactive is used to describe event-driven systems
   ! Reactive is used more for scalability and stability than
   for speed
   ! Reacts to resource availability
   6
   What is reactive?
   

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7. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
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   Use Case: Serve slow clients
   7
   Server
   

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8. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
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   Use Case: Serve slow clients
   8
   Server
   

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9. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
   
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   Use Case: Push message to client
   9
   Server
   Message Broker
   

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10. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    ! Live (continuous) database queries
    ! UI event handling (Android)
    ! Big Data
    ! Real time analytics
    ! HTTP/2 (flow control)
    10
    Other use cases
    

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11. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    ! Collaborative initiative to provide a standard for
    asynchronous stream processing with non-blocking back
    pressure.
    ! Co-designed by Twitter, Lightbend, Pivotal, Netflix and many
    others
    ! De-facto interop standard
    ! Java 9: Flow API
    11
    Reactive Streams
    

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12. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    Publisher and Subscriber
    12
    Subscriber
    Publisher
    Subscribe
    Data
    

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13. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    Publisher and Subscriber
    13
    Subscriber
    Publisher
    Publish as fast as possible
    

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    14
    Publisher
    I/O thread
    push
    

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    Back pressure control
    15
    Subscriber
    Publisher
    Demand
    

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16. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    Back pressure control
    16
    Subscriber
    Publisher
    Demand
    

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17. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    Spring WebFlux
    

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    ! Spring’s reactive web framework
    ! End to end non-blocking and asynchronous execution
    18
    What is WebFlux?
    

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19. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    ! Publisher to Publisher
    ! JSON (Jackson) and XML (JAXB/Aalto)
    ! Server-Sent Events
    ! Zero-Copy transfer of resources
    19
    Reactive Object Mapping
    

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    Reactive WebControllers
    20
    @GetMapping("/")
    Flux people() {
    return personRepository.findAll();
    }
    @GetMapping("/people/{name}")
    Mono person(@PathVariable String name) {
    return personRepository.findByName(name);
    }
    @PostMapping("/people")
    Mono addUser(@RequestBody Mono person) {
    return personRepository.save(person);
    }
    

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21. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    Non-blocking
    21
    @GetMapping("/people/{name}")
    Person person(@PathVariable String name) {
    return new Person(name);
    }
    @GetMapping("/people/{name}")
    Mono person(@PathVariable String name) {
    return personRepository.findByName(name);
    }
    

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22. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    Reactive Web Client
    22
    WebClient client = WebClient.create();
    client.get() //
    .uri("/api/people?count={count}", 10)
    .retrieve()
    .bodyToFlux(String.class)
    .doOnNext(item -> …)
    .blockLast();
    

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23. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    Router Functions
    23
    RouterFunction> routes = route(GET("/"),
    request -> ServerResponse.ok().build())
    .and(route(POST("/people/{name}")
    .and(accept(MediaType.APPLICATION_JSON)),
    request -> ServerResponse.accepted().build()))
    .and(resources("/static", new ClassPathResource(…)));
    HttpHandler handler = RouterFunctions.toHttpHandler(routes);
    HttpServer server = HttpServer.create(8080);
    server.startAndAwait(new ReactorHttpHandlerAdapter(handler));
    

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24. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    24
    

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25. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    Spring Data
    

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    Accessing Data today
    26
    Request Data access
    Remote data
    service
    I/O Wait
    
    This one is
    waiting
    

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    Accessing Data today
    27
    Request Data access
    Remote data
    service
    Multiple
    calls
    Bulk fetch
    
    

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    ! Keep resources busy
    ! Connection contention
    ! Usually synchronous/blocking
    ! Multiple requests
    ! Asynchronous isn’t always a good answer
    28
    Todays’ data access
    

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29. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    ! Project Reactor 3.0
    ! Spring Framework 5.0
    ! Spring Data 2.0
    ! A reactive (asynchronous, ideally non-blocking) driver
    ! Optional: Spring Boot 2.0
    29
    Requirements for Reactive Spring Data
    

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    ! Non-blocking I/O
    ! Threading-infrastructure
    ! Back pressure
    ! Integration with reactive libraries
    30
    Why reactive drivers?
    

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    ! MongoDB
    ! Apache Cassandra
    ! Redis
    ! Couchbase
    31
    Reactive Spring Data modules
    

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32. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    ! JDBC is a blocking API
    ! JPA is a blocking API
    ! Sorry, no reactive JPA support
    32
    What about JPA
    

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33. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    ! Reactive Template API
    ! Reactive Repository support
    ! Reduced feature set
    33
    Reactive Spring Data
    

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34. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    34
    Imperative Template API
    T insert(T objectToSave)
    void insertAll(Collection<…> objects)
    

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35. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    35
    Reactive Template API
    Mono insert(T objectToSave)
    Mono insert(Mono objectToSave)
    

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36. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
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    36
    Reactive Repository API
    public interface ReactivePersonRepository extends
    ReactiveCrudRepository {

    

    Flux findByLastname(String lastname);

    

    @Query("{ 'firstname': ?0 }")

    Mono customQuery(String firstname);
    Flux findByLastname(Mono lastname);
    }
    

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37. public interface ReactivePersonRepository extends
    ReactiveCrudRepository {

    

    Flux findByLastname(String lastname);

    

    @Query("{ 'firstname': ?0 }")

    Mono customQuery(String firstname);
    Flux findByLastname(Mono lastname);
    }
    Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    37
    Reactive Repository API
    

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38. public interface ReactivePersonRepository extends
    ReactiveCrudRepository {

    

    Flux findByLastname(String lastname);

    

    @Query("{ 'firstname': ?0 }")

    Mono customQuery(String firstname);
    Flux findByLastname(Mono lastname);
    }
    Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    38
    Reactive Repository API
    

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39. public interface ReactivePersonRepository extends
    ReactiveCrudRepository {

    

    Flux findByLastname(String lastname);

    

    @Query("{ 'firstname': ?0 }")

    Mono customQuery(String firstname);
    Flux findByLastname(Mono lastname);
    }
    Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    39
    Reactive Repository API
    

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40. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Questions?
    Mark Paluch • @mp911de
    https://github.com/mp911de/reactive-spring
    https://mp911.de/reactive-spring
    

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41. Unless otherwise indicated, these slides are © 2013-2017 Pivotal Software, Inc. and licensed under a
    
    Creative Commons Attribution-NonCommercial license: http://creativecommons.org/licenses/by-nc/3.0/
    Resources
    ! Code - Repository @ Github
    ! Reactor Rx Lite API – Repository @ Github
    ! Spring Data Examples – Repository @ Github
    ! Spring projects release calendar – Google Calendar
    41
    @mp911de
    

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